Lead for radio systems



H. J. WRAPE LEAD FOR RADIO SYSTEMS Jan. 2l, 1930.

Original Filed Aug. 18. 1922 llil--Ilqf Patented'. Jan. 21 1930.'

UNITED STATES PATENT OFFICE HAROLD J. WRAPE, IO1? ST. LOUIS, MISSOURI, ASSIGNOR, BY MESNE ASSIGNMENTS, TO BENWOOD-LINZE COMPANY, OIEl ST. LOUIS, MISSOURI, A CORPORATION OF MISSOURI nected to the service mains and the current' LEAD FOR RADIO SYSTEMS Original application filed August 18, 1922, Serial No. 582,736. Divided and this application led July 19,

, 1929. Serial No. 379,403.

The invention pertains to apparatus for use in wireless telegraphy and telephony.

This application is a division of applicae tion Serial No. 582,736, iiled August 18, 1922.

In many installations of radio apparatus, condensers are required to furnish the required electrical capacity for proper tuning operations, adjustment of wave lengths, and similar purposes. In many' cases the actual value of the capacity required is extremely small, and values as low as 1/100 to 1/1000 of a microfarad being used. In such cases the dimensions of a condenser constructed for such small capacity become very small. In fact, two parallel wires of several' eetin length have been found to have between them Suilicient capacity for some purposes.

One of the objects of this invention, there fore, is to provide a connecting lead for use with radio apparatus which shall have incorporatedtherein a condenser of small capacity.

It is often found inconvenient or expensive to erect the necessary' antenna required for receiving or' transmitting radio signals. In many cases it is found convenient to utilize in place of the antenna, an existing network of conductors suchas, for instance, the electric light wiring of an Ordinary house. Some diiiiculty is encountered in connecting to the light Wiring of an ordinary house, on account of the fact that such wiring is always confrom such mains'must be kept out of the radio apparatus.

Another object of this invention. therefor is to provide a.connecting lead or leads through which the radio setmay be connected y to the house wiring as an antenna without incomprising a pair of wires, 2.

method of connecting to the house wiring through leads embodying this invention.

Fig. 2 is a sectional view of a conductor embodying this invention.

Referring to the drawing, l designates a lead which is made up of a pair of wires 2, each of which'may be provided with its own insulation 3. The two insulated wires are enclosed ina common insulated covering 4: which may be provided at its ends with caps 5 to provide a closure therefor and to finish the end. One of the insulated conductors is arranged to protrude from each of the caps 5 and its protruding end is provided with a terminal 6 by meansof which an electrical connection may be made thereto. In each conductor the end of the wire 2, Opposite the terminal 6 is cut and insulated so as to be dead-ended. This end of the insulated conductor may be provided with a cap 7 to which may be attached a flexible cord 8.

The conductors are mounted so that they may Slide in the covering 4 which may be av flexible covering. Thus either or both conductors may be drawn out of the covering by pulling on the terminal end thereof and may be drawn back into the covering by drawing on the cord 8. In this way the lengths of wire of the two conductors which are adjacent to one another may be varied.

These adjacent lengths of wire provide a condenser, the capacity of which varies in accordance with the lengths of conductors which are adjacent to each other. Accordingly a lead so constructed'provides a-condenser of small capacity and whose capacity may be adjusted by drawing the conductors into or out of the covering 4.

In'using this device the connection is made as illustrated in Figure l, in which 9, desig nates the house wiring, designates one coil of a radio transformer, of which 1l is the other coil. The coil 10 is connected to the main 9 through a pair of leads, l, each lead It will be noted that one of each pair of wires 2, is connected to the mainsb), while the other conductor, 2, of each pair is connected to the coil 10. It will be noted that there is thus no conductive connection between the mains 9,

and the coil l0, so that practically "none of the service current from the house circuit will flow through the coil, 10.. Only such current as can pass through the condenser formed by the Wires, '2, can flow and, since the voltage .and frequency on the mains, 9, are comparatively very low, only a negligible current Will flow from the mains through the coil l0.

The conditions that obtain with this con-l nection, are however, very favorable for use in radio Work. It will be understood that in ordinary house Wiring one of the mains, 9, is grounded While the other is not. It Will be evident, therefore, that by this connection one terminal ofthe coil, 10, Will' be connected through a hght condenser to a network of Wires adapted to providewan effective an.

tenna. It is true that the grounded` and ungrounded mains are connected together vthrough the secondary coil of the service transformer. The inductance of such a coil is, however, so high that currents of radio frequently will notglowv therethrough, so that l the` presence of. such al coil Will-not affect the operation of the system for radio Work.

While in the large majority of cases one side of the house Wiring is grounded, there are some cases in which thehouse circuit is not grounded. In such case the radio set may be connected to vone side of the'house circuit by means offa single lead, and to the ground through a separate lead.`

A-convenient way to arrange for connectio tothel housev circuit is to use a pair of leads such as shown'in Fig. 2, and connect oneterminal of each-to a terminal of an ordinary plug such as may be inserted in an-ordinary lamp socket. The 'other terminals of the leads'are then connected-to the radio set.

It will be evident from the foregoing that the invention accomplishes its objects. A device is providedvvhereby a radio set may be nection for the set. At the same time inlter' ference of the house circuit with the opera connected to the ordinary housel mains in l such a WayV that said mains Will furnish both the groundconnection and the antenna contion of the set is effectively prevented.

The connecting leads `also furnish the re'- quired small value of capacity for ordinary.

radio sets, particularly amateur sets of which a great many are `1n use.

It is lobvious that various changes may be I made inthe details of construction Without departing from the spirit of this invention; it is therefore to 'be understood that this invention is not to he limited to the'speciiic parallel ilar conductors which "are separated and arranged Within u common-covering, and

means for eliecting relative adjustment of said conductors in order to form a variable condenser.

3. I n a radio system, aleadfcomprising parallel Vvfilar conductors which are separated and arranged Within a common covering, and

means fordrawing said conduct-ors into and out of said covering in order to form a variable condenser.

4-In testimony whereof I atliX this 26th day of June, 1929.

' HAROLD J. WRAP-E.

my l signature A izo 

